Grinding and cutting body



l cc. i942 GRINDING AND CUTTING BODY Hans Bernstorfl,Frankfort-on-the-Main,

and

Gustav Jaeger, Neu-Isenburg, Germany; vested in the Alien PropertyCustodian No Drawing. Application October 21, 1940, Serial No. 362,154.In Germany October 4, 1939 4 Claims.

Our invention relates to the manufacture of grinding bodies and cuttingbodies from metal alloys, particularly alloys containing beryllium, forexample, copper-beryllium, iron-beryllium, nickle-beryllium.

Ceramic materials and hard substances are usually treated with grindingor cutting discs made from heavy metals or alloys of heavy metals, forinstance, steel or any other iron alloy in which the abrasive, forexample, diamond dust, is embedded. These discs have the disadvantage tobe worn oil rather quickly as the grip of the abrasive grains in thebase material is not firm enough to stand the high stress.

Recently abrasive and cutting discs have been known whereby the abrasive(diamond dust) is pressed into an alloy of iron, cobalt and nickel.lhese discs are in fact extraordinarily hard but have the disadvantagethat they cannot be used up sufificiently. If, in using these abrasivesthe diamond grains are ground to spherical bodies they are not rubbedofi and do not give way to the deeper lying diamond grains but areincapable to move owing to the hardness of the base material. Inconsequence thereof a suflicient grinding or cutting efiect ceases aftera relatively short employment.

Now we have found that certain alloys of heavy metals such as copper,iron or the like with beryllium show mechanical properties which areexcellently suited for the utilization as base material for abrasives,for example, diamond dust or the like.

Very good results have been obtained with copper-beryllium alloys with aberyllium content of 2 to 5% by weight. Such alloys have a considerabletenacity, warranting a firm grip of the abrasive. Besides, the necessaryusing up through abrasion of the worn abrasive grains from the eflectivesurface is not limited. The tendency of spontaneous structuralchangement of these alloys is very low and fractures through repetitionof stress are therefore--in comparison with the hitherto knowndiscs-only rarely occurring. Good results were also obtained with alloysof iron and nickel with beryllium or an alloy of iron-nickel-beryllium.The content of beryllium depends to a certain extent upon the content ofthe heavy metal or heavy metals alloyed therewith. Thus, for instance,it has proved advantageous to keep the beryllium content inironberyllium alloys somewhat higher than in copper-beryllium alloys,especially if abrasives or produced. The content of beryllium may beabout 10% by weight or even more. If different quantities of berylliumare added the qualities of the base material are influenced with respectto hardness, tenacity, structural stability or the like. In this mannerabrasive bodies will be obtained with special suitability for certainpurposes. In each case the best suited heavy metals and the content ofthe beryllium may be ascertained by simple preliminary tests.

The alloys of copper, iron, nickel with beryllium may also containinferior quantities of other metals, for instance, of tungsten,molybdenum, chromium, vanadium either alone or in mixture. The additionsmay influence the qualities of the alloys to a certain degree.

The manufacture of the alloys of heavy metals according to our inventionis carried out by a sintering process, expediently in such manner that apulverulent mixture of the substances is heated to temperatures not farbelow the melting point. The sintering is preferably carried .out attemperatures as high as possible whereby melting is avoided. Theabrasive material, for instance, diamond dust, diamond splits, siliciumcarbide, boron carbide, beryllium carbide, or mixtures thereof, areembedded into the heavy metal-beryllium alloy during the workingoperation. According to our invention we may also proceed in such mannerthat the abrasive material is applied to the base material and then moreor less sintered into the base material.

The heavy metal-beryllium alloys according to our invention possess thegreat advantage that after quenching they may be easily worked up, i.e., drilled, milled, cut or the like. They may also be tempered with theefiect of improved qualities with respect to hardness, tenacity and thelike. The tempering may, for instance, be carried out, in such mannerthat the article to be tempered is heated to a suitable temperaturebelow the melting point, quenched and tempered by heating at suitable,preferably moderate temperatures. According to the conditions of thetempering process the mechanical properties of the final material may beinfluenced as desired.

The hardness of a copper-beryllium alloy with about 2 to 5% by weight ofberyllium shows after quenching to 150 Brinell and after one hourtempering at temperatures of 350 C. about 300 to 400 Brinell, even 500Brinell. The hardness of a nickel-beryllium alloy with 2% of weight B.is after quenching, for instance, Brinell and cutting bodies of elevatedhardness are to be 55 after tempering at a temperature of 400 C. duringa period of 36 hours, the hardness will be increased to about 450Brinell. Iron-beryllium alloy with 4% by weight of B. quenched,possesses about 250 Brinell and after tempering at a temperature of 450C. the hardness increases to about 520 Brinell. An alloy, consisting of10% nickel, 1% beryllium, rest iron shows a hardness of about 350Brinell in a quenched state and after tempering at a temperature of 450C., the hardness will increase to about 611 Brinell.

The process for the production of abrasive and cutting bodies will beillustrated by the following examples:

(1) Copper powder is intimately mixed with a suitable amount ofberylliumpowder (preferably between 2 and 5% by weight) and a suitablequantity of diamond dust, the mixture coldpressed to a shaped body andsintered under pressure. The sinterlng temperature is expediently chosenin such manner that it lies not far below the melting point of the finalalloy in order to facilitate the formation of the alloy by way ofdifiusion. The pressure is thus rated that the disc obtains anespecially suitable strength for its special purposes. The sintered bodyis then quenched and subjected to an after treatment. Subsequently thesintered body will be tempered according to the usually known methods inorder to obtain its final properties.

Instead of coldpressing the pulverized mixture may be applied to asuitable form and sintered under pressure whereby forming and diffusionare carried out at one single operation step.

(2) A mixture of heavy metal powder, for instance, copper powder andberyllium powder are pressed without addition of an abrasive mate: rial.To the surface or effective area, for instance, cutting area of thisbody, a layer of an abrasive of a suitable thickness is applied,whereupon the abrasive will be sintered with pressure into the basematerial.

What we claim is:

1. A grinding and cutting body consisting of a tempered, sinteredcarrier composed of an alloy of beryllium and a metal selected from thegroup consisting of copper, iron and nickel, and an abrasive embeddedtherein.

2. A grinding and cutting body consisting of a tempered sintered carriercomposed of an alloy of copper and beryllium, the beryllium bein presentin a quantity of 2% to 5% of the alloy. and diamond dust embeddedtherein as an abrasive.

3. A process for producing a grinding and cutting body composed of asintered carrier composed of an alloy of 2% to 5% of beryllium andcopper and diamond dust embedded therein, which comprises mixingberyllium powder with copper powder and diamond dust, the quantity ofberyllium being sumcient to form an alloy containing 2% to 5% ofberyllium with said copper, sintering the mixture under pressure toeflect alloying of the copper beryllium quenching the sintered body, andsubsequently tempering such body.

4. A process for producing a grinding and cutting body composed of asintered carrier composed of an alloy of beryllium and a metal selectedfrom the group consisting of copper, iron and nickel, and an abrasiveembedded therein, which comprises mixing beryllium powder with powder ofa metal selected from the group consisting of copper, iron and nickeland an abrasive, sintering the mixture under pressure to eflect alloyingof the metals therein, quenching the sintered body, and subsequentlytempering such body.

HANS BERNS'IORFF. GUSTAV JAEGER.

